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PDBsum entry 2n4x
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Membrane protein
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PDB id
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2n4x
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References listed in PDB file
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Key reference
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Title
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Structure and multistate function of the transmembrane electron transporter ccda.
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Authors
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J.A.Williamson,
S.H.Cho,
J.Ye,
J.F.Collet,
J.R.Beckwith,
J.J.Chou.
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Ref.
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Nat Struct Biol, 2015,
22,
809-814.
[DOI no: ]
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PubMed id
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Abstract
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The mechanism by which transmembrane reductases use a single pair of cysteine
residues to relay electrons between protein substrates across biological
membranes is a long-standing mystery in thiol-redox biochemistry. Here we show
the NMR structure of a reduced-state mimic of archaeal CcdA, a protein that
transfers electrons across the inner membrane, by using a redox-active NMR
sample. The two cysteine positions in CcdA are separated by 20 Å. Whereas one
is accessible to the cytoplasm, the other resides in the protein core, thus
implying that conformational exchange is required for periplasmic accessibility.
In vivo mixed disulfide-trapping experiments validated the functional
positioning of the cysteines, and in vitro accessibility results confirmed
conformational exchange. Our NMR and functional data together show the existence
of multiple conformational states and suggest a four-state model for relaying
electrons from cytosolic to periplasmic redox substrates.
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